It was disclosed in European Patent Application Laid Open No. 192,060 and Japanese Patent Application Laid Open No. 171/1990 that 2-chloro-5-(chloromethyl)thiazole of the formula ##STR2## (optionally called compound [I] hereinbelow) and 5-(aminomethyl)-2-chlorothiazole of the formula ##STR3## (optionally called compound [III] hereinbelow) or salts thereof are useful as an intermediate for insecticides. There is, however, only a specific process disclosed in Japanese Patent Application Laid Open No. 83979/1988 for preparing compound [I] in which allyl isothiocyanate is reacted with a chlorinating agent as illustrated below. ##STR4## This process needs a large excess of the chlorinating agent, high temperature and furthermore involves a very vigorous reaction. Consequently, a plurality of by-products is formed in addition to merely a small amount of the desired compound [I] in the reaction, and separation thereof from the by-products is troublesome. Thus the isolated yield of compound [I] results in quite low. The process therefore can by no means be considered as a good process for preparing compound [I].
Japanese Patent Application Laid Open No. 171/1990 also discloses a process comprising reaction of compound [I] with potassium phthalimide as a process for preparing compound [III]. However, a simpler, less costly and higher yield process is desired.
Such being the case, it is an object of the invention to provide a process for preparing 2-chloro-5-(chloromethyl) thiazole (compound [I]) from an allyl isothiocyanate derivative represented by the formula [II] shown below (optionally called compound [II] hereinbelow) by simple and convenient reaction procedures under mild conditions without need of a large excess of a chlorinating agent, a process for preparing 5-(aminomethyl)-2-chlorothiazole [III] or salts thereof from compound [II] via compound [I] and a novel process for preparing compound [III] or salts thereof in a higher yield by simple, convenient and inexpensive procedures.